Simplify the following expression: $t = \dfrac{r^2 + 4r - 60}{r - 6} $
Answer: First factor the polynomial in the numerator. $ r^2 + 4r - 60 = (r - 6)(r + 10) $ So we can rewrite the expression as: $t = \dfrac{(r - 6)(r + 10)}{r - 6} $ We can divide the numerator and denominator by $(r - 6)$ on condition that $r \neq 6$ Therefore $t = r + 10; r \neq 6$